AOL plans to launch later this year a program that will allow third-party developers to develop applications and content, including instant messaging and social networking, for its e-mail sites.

"We are opening up the panel architecture in Web suite, which is the content portion of Web mail, to third-party developers by the end of this year," said Richard Landsman, senior vice president for mail product and technology at AOL, in an interview on Thursday. "Once that is opened up, technically, there is no reason why somebody cannot create some other IM mashup or some other IM client that can be plugged in there," he added.

The strategy reflects AOL's recognition that users will want some applications and content from competitors like Google and Yahoo, and no single company can control all the applications that users will want to use, Landsman said.

Panels developed by third-party developers will be included on AOL's mail sites in various countries, giving the user the option to choose a variety of content, and integrate AOL mail with popular applications in local markets, Landsman said. AOL will however have some process in place to ensure that, for example, a third-party application on its site does not behave maliciously, he added.

Having already integrated its AOL Instant Messenger (AIM) into its e-mail, AOL also plans to integrate the ICQ instant messenger with its mail application this year in certain markets where ICQ is popular, said Roy Ben-Yoseph, AOL's vice president for mail products.

The company will also offer ICQ mail as a separate domain under its Affinity domains program, which allows a user to customize an AOL mail address by using a domain name of their choice instead of the default aol.com, Ben-Yoseph added. ICQ became part of AOL after it acquired Mirabilis in 1998, but has been run as a separate service.

AOL is also including Microsoft's Silverlight multimedia technology to deliver a new high-performance, Web mail application, Landsman said. Silverlight is a cross-platform plug-in that lets developers create multimedia and rich Internet applications and then run them from the browser. The mail product from AOL will probably go into beta testing by the third quarter of this year, Landsman said. AOL plans to use the flexibility offered by Silverlight to give users the ability to change the user interface, change skins, themes, and also change the organization of the mail, Ben-Yoseph said.